[OpenLayers-Users] How to use bbox in long/lat with google/bing/etc... using mapserver

[Greg Allensworth]

On 1/21/2013 2:44 PM, Gery . wrote:
> The bbox of OpenLayers.Control.GetFeature works in utm
> when the baselayer is 900913 ie. google/bing/etc) and
> in long/lat when the baselayer is 4326

Correct. The control will use the map's SRS when stating the bbox.


> How can I force bbox to be in long/lat when I use one of
> my layers over google for example?

Two options:


1. Don't. Your WMS should support queries in multiple SRSs. If you're 
using MapServer, for example:

WEB
     METADATA
         "wms_title" "wms_mapfile"
         "wms_onlineresource" 
"http://domain.org/cgi-bin/mapserv?map=/my/wms.map&"
         "wms_srs"             "EPSG:3857 EPSG:900913 EPSG:4326"
     END
END


2. If you do want the bbox in your chosen SRS, you would need to 
subclass the GetFeatureInfo control and patch it to .transform() the 
bounding box. This UNTESTED JavaScript code for 
OpenLayers.Control.LatLonWMSGetFeatureInfo would would look something 
like this:


OpenLayers.Control.LatLonWMSGetFeatureInfo = 
OpenLayers.Class(OpenLayers.Control.WMSGetFeatureInfo, {

     buildWMSOptions: function(url, layers, clickPosition, format) {
         // call the parent class to get the options
         var opts = OpenLayers.Control.WMSGetFeatureInfo(url, layers, 
clickPosition, format);

         // replace the bbox with the one from the map, coerced into 
WGS84 coords
         var OLD_SRS = this.map.getprojectionObject();
         var SRS_LONLAT = new OpenLayers.Projection('EPSG:4326');
         opts.params.bbox =
             bbox: 
this.map.getExtent().transform(OLD_SRS,SRS_LONLAT).toBBOX(null,firstLayer.reverseAxisOrder());
             }

     // hand these back, as if nothing had happened
     return opts;
});


-- 
Greg Allensworth, Web GIS Developer
BS  A+  Network+  Security+  Linux+  Server+
GreenInfo Network - Information and Mapping in the Public Interest
564 Market Street, Suite 510  San Francisco CA 94104
PH: 415-979-0343 x302  FX: 415-979-0371    email: gregor at greeninfo.org
Web: www.GreenInfo.org     www.MapsPortal.org

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